In a new Stranger Things season 5 teaser, Netflix ended up revealing the in-universe date that the next part of the series starts, saying, "In the fall of 1987, one last adventure begins." That means there will be an 18-month time jump between the events of Stranger Things season 4 and 5. I think that is a good move, as the main actors of Stranger Things are now adults, and having them age in the show, even if it is just by a year and a half, can make their characters a bit more convincing.
